Advanced asymmetric supercapacitors based on Ni3(PO4)2@GO and Fe2O3@GO electrodes with high specific capacitance and high energy density

Abstract

Ni₃(PO₄)₂@GO composites were fabricated via a facile chemical precipitation method. More importantly, it was observed from electrochemical measurements that the obtained Ni₃(PO₄)₂@GO electrode showed a good specific capacitance (1392.59 F g⁻¹ at 0.5 A g⁻¹) and cycling stability (1302 F g⁻¹ retained after 1000 cycles at 1 A g⁻¹). In addition, a high-voltage asymmetric supercapacitor was successfully fabricated using Ni₃(PO₄)₂@GO and Fe₂O₃@GO as the positive and negative electrodes, respectively. The asymmetric supercapacitor could be cycled reversibly in the high-voltage region of 0–1.6 V and displayed intriguing performances with a maximum specific capacitance of 189 F g⁻¹ at a current density of 0.25 A g⁻¹. Furthermore, the Fe₂O₃@GO//Ni₃(PO₄)₂@GO asymmetric supercapacitor exhibited a high energy density of 67.2 W h kg⁻¹ and an excellent long cycle-life along with 88% specific capacitance retention after 1000 cycles. The impressive results presented here may pave the way for promising applications in high energy density storage systems.